Night Shift Work and Cancer Risk: What Medical Professionals Should Know
Updated: 6 days ago
The Health Risks of Shift Work
Shift work is essential to healthcare services, which must operate around the clock. However, working at night or on irregular schedules can disrupt the body's circadian rhythm — the internal system that regulates sleep and other biological processes. Over time, this disruption can contribute to sleep difficulties, fatigue and other health concerns.
Medical professionals, including doctors and nurses, may be particularly affected because of night duties, long working hours and limited opportunities for recovery between shifts. Understanding the potential health effects of shift work is important, both for protecting healthcare workers' wellbeing and for recognising the need for appropriate workplace support.
What Does the Evidence Say About Night Shift Work and Cancer?
Research into night shift work and cancer has raised concerns about the possible effects of long-term disruption to the body's circadian rhythm. In 2019, the International Agency for Research on Cancer (IARC), part of the World Health Organization, classified night shift work as “probably carcinogenic to humans” (Group 2A). This classification reflects limited evidence of cancer in humans, alongside evidence from experimental studies and biological mechanisms. It does not mean that night shift work will cause cancer in every person who works nights.
Some studies have reported associations between night work and cancers such as breast, prostate and colorectal cancer. However, findings differ between studies, and an association does not by itself establish that night shift work causes a particular cancer.
A 2025 systematic review and meta-analysis examining breast cancer risk among healthcare workers found no clear overall association with any night shift exposure. It did identify a possible increase among those with long-term exposure, but the researchers cautioned that the findings were not conclusive and were sensitive to limitations in the available studies.
For doctors, nurses and other healthcare professionals who regularly work nights, the evidence supports taking the potential health implications seriously without overstating what is known. It also highlights the importance of continued research and workplace approaches that reduce avoidable circadian disruption and support adequate recovery between shifts.
Consequences of shift work for medical professionals
Shift work can affect medical professionals' physical health, emotional wellbeing and relationships. Working at night or rotating between different shifts can disrupt sleep and make it difficult to obtain sufficient, restorative rest. Persistent sleep disruption may contribute to fatigue, reduced concentration and impaired alertness, which can affect both personal wellbeing and performance at work.
Irregular hours and limited recovery time can also make it harder to maintain social connections, participate in family life and sustain routines that support wellbeing. Over time, the combination of demanding workloads, sleep difficulties and ongoing occupational stress may contribute to emotional exhaustion and burnout.
These effects vary between individuals and depend on factors such as shift patterns, workload, recovery time and personal circumstances. It is therefore important to recognise that difficulties associated with shift work are not simply a matter of individual resilience. Workplace scheduling, staffing levels and opportunities for adequate rest also play a role in protecting healthcare professionals' health and wellbeing.
Reducing the Health Impact of Shift Work
Although medical professionals may have limited control over their shift patterns, there are practical steps that can help reduce the impact of shift work on health and wellbeing.
Protect sleep and recovery time: Create a dark, quiet sleeping environment and aim for sufficient sleep after night shifts. Where possible, allow adequate recovery time between shifts.
Maintain supportive routines: Regular meals, physical activity suited to individual circumstances and time outdoors can support general health and wellbeing.
Take breaks when possible: Short breaks during shifts can provide opportunities to rest, eat and regain concentration, although they cannot fully compensate for insufficient sleep.
Stay connected: Make time for family, friends and activities outside work. Social connection can help support emotional wellbeing when working irregular hours.
Recognise when additional support is needed: Persistent fatigue, sleep difficulties, emotional exhaustion or declining wellbeing should not be ignored. Consider seeking appropriate healthcare or professional support.
Advocate for safer working conditions: Adequate staffing, manageable workloads, predictable scheduling and sufficient rest between shifts are important organisational responsibilities, not simply individual lifestyle choices.
These measures may help reduce some of the difficulties associated with shift work, but they cannot eliminate every potential health risk. Protecting medical professionals requires both individual strategies and workplace practices that recognise the demands of working irregular hours.
Conclusion
Shift work is an essential part of healthcare, but working at night and on irregular schedules can affect sleep, physical health, emotional wellbeing and family life. Research has also raised concerns about a possible link between night shift work and certain cancers, although the strength of the evidence varies and the risks for individuals remain uncertain.
Medical professionals can take steps to support their health and wellbeing, including protecting sleep, allowing time for recovery and seeking support when difficulties persist. However, individual strategies alone cannot address every risk. Safer scheduling, adequate staffing and manageable workloads are also important in protecting healthcare workers.
Recognising the potential effects of shift work is an important step towards supporting the people who provide care around the clock.
References
1. International Agency for Research on Cancer (IARC). (2020). Night Shift Work. IARC Monographs on the Identification of Carcinogenic Hazards to Humans, Volume 124. World Health Organization.
2. Schernhammer, E. S., Laden, F., Speizer, F. E., Willett, W. C., Hunter, D. J., Kawachi, I., Fuchs, C. S., & Colditz, G. A. (2003). Night-shift work and risk of colorectal cancer in the Nurses’ Health Study. Journal of the National Cancer Institute, 95(11), 825–828.
3. Esposito, G., Bravi, F., Santucci, C., Zunarelli, C., Violante, F. S., La Vecchia, C., Negri, E., & Turati, F. (2025). Night shift work and breast cancer risk in healthcare workers: A systematic review and meta-analysis. Occupational Medicine, 75(9), 596–607.
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